Fixtures and methods for lead bonding and deformation

ABSTRACT

In a method for mounting a sheet-like multi-layer element for producing a microelectronic component, the sheet-like element is first bonded to an expansion ring. The expansion ring is then heated to stretch the sheet-like element. A frame ring, having an external diameter smaller than the internal diameter of the expansion ring, is then bonded to the sheet-like element. The assembly is then cooled, and the expansion ring is cut away. In another embodiment, a method is provided for bonding bond pads on a sheet-like microelectronic element to terminal pads on a microelectronic component. The microelectronic element is first placed on a rigid plate and the sheet-like element, which has been bonded to a frame ring, is placed over the microelectronic component. A disk is then placed on the sheet-like element, and force is applied to the disk, bringing the bond pads on the sheet-like element into contact with the terminal pads on the microelectronic element. Heat is then applied, forming the bonds.

The present application claims benefit of U.S. provisional applicationSer. No. 60/001,718 filed Jul. 31, 1995, and is a file wrappercontinuation application of Application No. 08/440,665 filed May 15,1995, now U.S. Pat. No. 5,801,441 which application was a divisionalapplication of application Ser. No. 08/271,768, filed Jul. 7, 1994,which issued on May 21, 1996 as U.S. Pat. No. 5,518,964.

FIELD OF THE INVENTION

The present invention relates the fabrication of mounting and connectiondevices for use with microelectronic elements such as semiconductorchips.

BACKGROUND OF THE INVENTION

Complex microelectronic devices such as modern semiconductor chipsrequire numerous connections to other electric components. For example,a complex microprocessor chip may require many hundreds of connectionsto external devices.

Semiconductor chips have commonly been connected to electrical traces onmounting substrates using several alternative methods, including wirebonding, tape automated bonding and flip-chip bonding. Each of thesetechniques presents various problems including difficulty in testing thechip after bonding, long lead lengths, large areas occupied by the chipon the microelectronic assembly, and fatigue of the connections due tochanges in size of the chip and the substrate under to thermal expansionand contraction.

Numerous attempts have been made to solve the foregoing problems. Onestructure that has been used to successfully address these problems isthe "interposer" or "chip carrier", disclosed in commonly assigned U.S.Pat. Nos. 5,148,265, 5,148,266 and 5,455,390. Interposers according tocertain embodiments taught in these patents comprise a flexible,sheet-like element having a plurality of terminals disposed thereon.Flexible leads are used to connect the terminals with contacts on amicroelectronic component such an integrated circuit. The terminals maythen be used to test the microelectronic chip, and may be subsequentlybonded to a final microelectronic assembly. The flexible leads permitthermal expansion of the various components without inducing stresses inthe connection.

A compliant layer may be disposed between the microelectronic componentand the flexible, sheet-like structure. The compliant layer encapsulatesthe leads and facilitates connection of the terminals to a test deviceand/or to the final electronic assembly by compensating for variationsin component flatness and terminal heights.

Commonly assigned U.S. Pat. No. 5,518,964, hereby incorporated in itsentirety herein, discloses further improvements in microelectronicconnections. In certain embodiments of the '964 patent, a flexible,sheet-like element has a first surface with a plurality of elongated,flexible leads extending from a terminal end attached to the sheet-likeelement to a tip end offset from the terminal end in a preselected,first horizontal direction parallel to the sheet-like element. The tipends have bond pads for connection to a microelectronic component. Eachof the plurality of leads is simultaneously formed by moving all of thetip ends of the leads relative to the terminal ends thereof so as tobend the tip ends away from the sheet-like element. This is accomplishedby relative movement between the sheet-like element and themicroelectronic component.

The tip ends of the leads are initially attached to the sheet-likeelement. The initial position of the bond pads on the tip ends isthereby fixed in order to facilitate attachment to the microelectroniccomponent.

During or after forming the leads by displacing the microelectronicelement relative to the sheet-like element, a compliant material, suchas silicone, is injected between the microelectronic element and thesheet-like element. The compliant layer facilitates testing by providingan even pressure on all the terminals located on the flexible sheet-likeelement regardless of the flatness of the testing fixture. Similaradvantages are realized during final assembly.

In one method taught in the '964 patent for fabricating an assemblycomprising an interposer and a microelectronic chip, a flexible,multi-layer dielectric sheet-like element is stretched taut usingmechanical means. While the multi-layer sheet is maintained in the tautcondition, it is bonded to a ring-like generally circular frame so thatthe multi-layer sheet stretches across the central opening of the frame.The multi-layer sheet is bonded to the frame using a suitable hottemperature adhesive such as epoxy resin film, preferably on the orderof about 10 microns thick. The frame is formed from molybdenum becausethat material has coefficient of thermal expansion substantially equalto that of the silicon semiconductor part with which the assemblage willbe used in later steps. The flexible dielectric sheet-like element ismaintained in its stretched, taut condition by the molybdenum ring untilthe end of the process. The sheet is therefore maintained in a stable,repeatable condition for formation of the leads and for bonding to themicroelectronic component. The multi-layer dielectric sheet-like elementis then processed in order to form the leads, terminals and bonding padsnecessary to make connections between the microelectronic element andother components.

After terminals, leads, and other elements have been formed on thesheet-like element, the sheet-like element, together with the molybdenumring, is placed in a fixture on top of and adjacent to a wafercontaining an array of microelectronic chips. The fixture, part of ahot-air press or an autoclave, has ports for the pressurization andevacuation of volumes defined by the top and bottom surfaces of thewafer and the sheet-like element. The wafer and the sheet-like elementare next aligned by bringing the sheet-like element into registrationwith the wafer. One or both of those components are moved in thehorizontal x-y directions through the use of micrometer screw adjustingdevices. A microscope or machine vision system may be used inconjunction with fiducial markings on the components in order to assistin alignment.

Because the sheet-like element is continuously held taut throughout thelead-forming process and the aligning process by the same molybdenumframe, the leads remain in a constant, stable position with respect tothe sheet-like element and with respect to each other. Alignment withthe wafer is therefore precise over its entire area.

While the wafer and the sheet-like element are maintained in precisealignment, compressed inert gas such as nitrogen is admitted in order toincrease the pressure between a top plate of the fixture and thesheet-like element. This biases the sheet-like element downwardlytowards the wafer so that a bonding material on the bond pads located atthe tips of each lead is engaged with a contact on the microelectroniccomponent. Because pressure from the compressed gas exerts force equallyacross the area of the sheet-like element, contact engagement across thearea is assured regardless of the heights of the contacts.

While the gas pressure is maintained, the assembly is heated to atemperature sufficient to activate the bonding material at the bond padsin order to form metallurgical bonds between the tip ends of the leadsand the contacts of the microelectronic components on the wafer. Duringthis operation, the sheet-like component tends to expand at a rategreater than the rate of expansion of the silicon wafer. However,because the sheet-like element is held under tension by the molybdenumframe, the thermal expansion of the sheet-like element is substantiallytaken up in relieving the tensile stress. The actual movement offeatures on the sheet-like element due to thermal expansion isapproximately equal to the thermal expansion of the frame. The frame, inturn, has a coefficient of thermal expansion substantially equal to thatof the wafer. Therefore, features of the sheet-like element remain inalignment with features of the wafer during the heating process.

After the bond pads are bonded to the microelectronic component, anencapsulant is injected between the dielectric sheet and the wafer sucha silicone. The encapsulant is a flowable, curable dielectric materialsuch as silicone. The encapsulant may be injected between the dielectricsheet and the wafer immediately after bonding, whereby the force of thepressurized encapsulant acting on those components separates them andbends the leads, forming a compliant lead configuration.

Alternatively, the leads may be formed before injecting the encapsulantby retaining the wafer and the sheet-like element against moveableplatens by vacuum, and moving the platens with respect to each other,bending and forming the leads. The encapsulant is then injected whilethe dielectric sheet and the wafer are in their displaced positions.

The injection operation is performed either using the same fixture inwhich the bonding step is performed or in a second fixture. The flowablematerial is constrained between the flexible sheet and the wafer, anddoes not cover the terminal features on the top surface of thedielectric sheet which remain exposed for testing and for permanentbonding to a microelectronic assembly.

After the flowable, curable dielectric material has been cured, theflexible sheet/microelectronic component assembly is removed from thefixture, trimmed and tested. The fixture is then reused to perform theabove operations on the next flexible sheet/dielectric componentassembly.

Still further improvement in the above-described process would bedesirable.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a method for mounting asheet-like, microelectronic element in which the sheet-like element isinitially bonded to an expansion ring. The expansion ring is thenheated, inducing thermal expansion that stresses the sheet-like elementuniformly taut. The sheet-like element is then bonded to a frame ringhaving an outside diameter less than the inside diameter of theexpansion ring. The expansion ring consists of a material having arelatively high coefficient of thermal expansion, and may have acoefficient of thermal expansion greater than that of molybdenum. Mostpreferably, the material is aluminum. The frame ring advantageously hasa coefficient of thermal expansion approximating that of silicon, andmay consist essentially of molybdenum. Preferred methods according tothis aspect of the invention provide reliable, repeatable and uniformstretching of the sheet at very low cost.

In another aspect of the invention, a method is provided for bonding aplurality of bond pads disposed on a flexible, sheet-likemicroelectronic element to a plurality of contacts on a microelectroniccomponent. The method includes the steps of mounting the flexible,sheet-like element to a frame ring, placing the microelectroniccomponent on a rigid plate, and then placing the frame ring on the rigidplate so that the sheet-like element overlies the microelectroniccomponent. The bond pads on the flexible sheet-like element are thenaligned with the contacts on the microelectronic component by moving theelement and the component in relation to one another. A disk is thenplaced on the top of the sheet-like element, and downward pressure isapplied to the disk, whereby the bond pads are pressed against thecontacts. The entire assembly is then heated, activating a bonding agentat an interface between the bond pads and the contacts. In this method,the rigid plate and/or the frame ring may consist essentially ofmolybdenum and the disk may consist essentially of ceramic. The assemblymay be heated by placing the rigid plate on a hot plate.

The bond pads on the sheet-like element may be at the ends of deformableleads formed on the sheet-like element. The method may further comprisethe step of bending the deformable leads. The leads may be bent bypressure forces of an encapsulant injected between the sheet-likeelement and the microelectronic component, or may be bent bymechanically displacing those two components in two directions.

Preferred methods according to this aspect of the invention perform thepad bonding step without use of the fixture used for moving the sheetand injecting. Thus the fixture can be used with one set of parts whilethe bonding step is being performed on the next set of parts. Thecompliant material cannot interfere with the alignment and bondingoperation.

In yet another aspect of the invention, a method is provided for bondinga plurality of bond pads disposed on a flexible, sheet-like element to aplurality of contacts on a microelectronic component. The methodcomprises the steps of bonding the sheet-like element to an expansionring, heating and expanding the expansion ring to stretch the sheet-likeelement taut, and bonding the sheet-like element to a frame ring, theframe ring having an outside diameter less than an inside diameter ofthe expansion ring. The microelectronic component is then placed on arigid plate, and the frame ring with the sheet-like element is placedover the microelectronic component. The bond pads on the sheet-likeelement are then aligned with the contacts on the microelectroniccomponent by moving the rigid ring and the component in relation to oneanother. A disk is then placed on the sheet-like element and downwardpressure is applied on the disk to press the bond pads against thecontacts. The assembly is then heated to activate a bonding agent at theinterface between the bond pads and the contacts.

These and other objects, features and advantages to the presentinvention, will be more readily apparent from the detailed descriptionof the preferred embodiments set forth below, taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the multi-layer, flexible, sheet-likeelement used in the manufacture of a component according to oneembodiment of the invention;

FIG. 2 is a plan view of elements used in the manufacture of a componentaccording to one embodiment of the invention;

FIG. 3 is a plan view similar to FIG. 1 but at a progressively laterstage of the process;

FIG. 4 is a plan view of the elements of FIG. 2 after the removal of anelement according to one step in the process;

FIG. 5 is a schematic view of a lead used in a process according to oneembodiment of the invention;

FIG. 6 is a sectional view of elements used in the manufacture of acomponent according to one embodiment of the invention;

FIG. 7 is a sectional view similar to FIG. 5, depicting the elements ata later stage of the process;

FIGS. 8-10 are diagrammatic sectional views depicting steps in themanufacturing process at successively later stages; and

FIG. 11 is a diagrammatic plan view depicting a preferred embodiment ofa lead used in the manufacturing process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A process for manufacturing components according to one embodiment ofthe invention begins with a starting multi-layer sheet-like element 30.The multi-layer sheet 30 includes a dielectric sheet 34 (FIG. 1)preferably formed from a polymer such as polyimide. Dielectric sheet 34is preferably between about 25 and about 100 microns thick and morepreferably between about 25 and 50 microns thick. The top layer 36 ofelectrolytically deposited copper covers the top surface 35 of thedielectric sheet 34, whereas a similar bottom layer 38 covers theopposite, bottom surface 37 of the dielectric sheet. The copper layersmay be from about 5 to about 25 microns thick. In the starting conditionillustrated in FIG. 1, these layers are continuous and substantiallyuniform over the entire extent of multi-layer sheet 30.

In order to further process the multi-layer, sheet-like element 30, theelement must be stretched taut and bonded to a frame ring have acoefficient of thermal expansion approximately equal to that of silicon,the material comprising the semiconductor wafer to which the sheet willbe bonded in a later step of the process. To stretch the sheet-likemulti-layer element taut, the multi-layer element 30 is first bonded toan expansion ring 11 (FIG. 2). The sheet is maintained flat and isassembled to the expansion ring 11 with a suitable high-temperatureadhesive therebetween. The adhesive is preferably an epoxy resin film.The ring 11 is preferably formed using a material having a relativelyhigh thermal coefficient of expansion, and is most preferably aluminum.During the assembly step, the expansion ring 11 and the sheet-likeelement 30 are at a first temperature below that used in the later stepsof the process, preferably below about 10 deg. C. and most preferably atabout room temperature.

After assembly, the expansion ring 11 and the multi-layer sheet-likeelement 30 are placed in a high temperature oven and heated to a secondtemperature higher than the first. While the ring and the epoxy resinare maintained at the second temperature, the epoxy resin is fullycured, bonding the sheet-like element to the expansion ring. Theexpansion ring is maintained at the second temperature for a period oftime in order to assure that the epoxy is fully cured before proceedingto the next step as described below.

In one example of the invention, an aluminum ring one inch thick havinga ten inch outer diameter and an eight inch inner diameter is coated onone surface with epoxy resin, placed on a polyimide sheet, and placed inan oven at 150 deg. C. for one hour. The heat cures the adhesive,bonding the polyimide sheet to the aluminum ring. In addition, thealuminum ring is partially expanded during this operation.

The expansion ring, together with the sheet-like element 30, is nextremoved from the oven and placed on a flat surface with the sheet-likeelement facing the surface. A second, or frame ring 12, having anoutside diameter smaller than the inside diameter of the expansion ring11, is coated with epoxy resin on a bottom surface and placed on thesheet-like element 30 inside the expansion ring (FIG. 3). The assemblyis then returned to the oven which is heated to a third temperaturehigher than the second temperature, most preferably about 170-180 deg.C. The increase in temperature increases the diameter of the expansionring and stretches the sheet-like element taut. When the assemblyreaches thermal equilibrium at the third temperature, the sheet-likeelement is stretched taut evenly in all directions by the evenly heatedring. The expansion ring, which had previously been preheated to thesecond temperature, reaches equilibrium at the third temperature longbefore the frame ring and the accompanying epoxy is heated. Therefore,the sheet-like element 30 is stretched taut and in equilibrium beforethe epoxy on the frame ring 12 cures. The two stage heating processassures that the sheet-like element 30 is stretched taut after curingthe epoxy bond with the expansion ring 11 but before curing the epoxybond with the frame ring 12.

The assembly is then removed from the oven and cooled. The expansionring is removed by severing the sheet-like element 30 between theexpansion ring 11 and the frame ring 12.

The frame ring 12 must have a coefficient of thermal expansion lowerthan that of the expansion ring 11 in order to maintain tautness in thesheet-like element 30 when the assembly is returned to room temperature.Aluminum is used to construct the expansion ring 11 because of itsrelatively high thermal expansion properties. Because the sheet-likeelement 30 will be bonded to a silicon wafer in later steps of theprocess, it is important that the sheet-like element, as bonded to theframe ring 12, behave thermally like silicon in order to maintainalignment of terminals on the chip and bond pads on the sheet-likeelement across the entire surfaces of these elements. Molybdenum is usedin constructing the frame ring 12 because molybdenum has a thermalexpansion properties similar to those of silicon.

The multi-layer sheet-like element 30, together with the frame ring 12,as shown in FIG. 4, are now ready for processing in order to form theleads and other microelectronic components on the surfaces of thesheet-like element 30. The leads and other microelectronic elements areformed by applying electrophoretic resist, electroplating, etching, andother techniques for forming microelectronic circuitry known in the art.A detailed description of such a manufacturing process is contained inU.S. Pat. No. 5,518,964, assigned to the same assignee as the presentapplication and hereby incorporated herein in its entirety.

A lead 41 formed as part of the sheet-like element 30 according to sucha process is attached to the polyimide sheet 34 at a terminal end 45(FIG. 5). The terminal end 45 is attached through a blind via 43 to aterminal 44 on the opposite side of the polyimide layer 34. The oppositeend of the lead 41 has a bond pad 42 for bonding to a microelectroniccomponent. The leads are arranged in a substantially regular pattern onthe sheet-like element 30, commonly in rectangular grids having constantpitches in the x and y directions. The grid pattern of leads of thesheet-like element 30 matches a grid pattern of terminals on themicroelectronic component to which the sheet will be bonded.

After formation of the microelectronic leads 41, terminals 44 and bondpads 42, the bond pads 42 are bonded to corresponding terminal pads 50(FIG. 8) on microelectronic element 51. This involves aligning the bondpads 42 with the terminal pads 50, bringing them into contact, andheating them to activate a bonding agent present at the interfacebetween the bond pads and the terminal pads.

In the case where the microelectronic component comprises a large arrayof chips, tens or even hundreds of thousands of terminal pads must bebrought into contact with corresponding bond pads on the sheet-likeelement. It is critical in bonding such a microelectronic component thatforce be applied evenly across the array regardless of the height of theindividual terminal pads and bond pads. For this reason, a hot airpress, also known as an autoclave, is used to pressurize the volumeabove the sheet-like element, applying an equal force to each of thethousands of bond pads. Such a process, however, may not be necessary inthe case of a microelectronic element comprising only a single chip or asmaller array of chips, such as a 3×3 array of chips.

In a process especially suitable for bonding to microelectroniccomponents comprising a single chip or a smaller array of chips, themicroelectronic element 51 is placed on a rigid base sheet 60 (FIG. 6).The base sheet 60 preferably has a coefficient of thermal expansionmatching that of the silicon wafer in order to reduce or eliminaterelative movement between the wafer and the base sheet, which in turncould affect the alignment described below. The sheet 60 may becomprised of molybdenum. If a material other than silicon is used inconstructing the microelectronic component 51, then the base sheet 60should be fabricated of a material having a coefficient of thermalexpansion matching that of the microelectronic component.

The sheet-like element 30, which remains bonded to the frame ring 12, isplaced over the microelectronic component. The face of the frame ring 12to which the sheet-like element 30 is bonded faces away from the basesheet 60. The rigid ring 12, together with the sheet-like element 30,are then manipulated on the base sheet 60 in order to align themicroelectronic features on the sheet-like element 30 with correspondingmicroelectronic features on the microelectronic component 51. Amicroscope may be used in this alignment procedure. Alternatively, amachine vision system 49, which may incorporate a microscope, may beused.

After aligning the sheet-like element 30 with the microelectroniccomponent 51, a disk 61 (FIG. 7) is placed on the sheet-like element 30.The disk is preferably fabricated from ceramic, although other thermallystable materials may be used. The disk 61 has a diameter smaller thanthe inside diameter of the frame ring 12, but the same or larger thanthe external diameter of the microelectronic component 51. The weight ofdisk 61 deflects the sheet-like element 40 downward toward themicroelectronic component. The deflection illustrated in FIG. 7 isgreatly exaggerated in the drawing for clarity of illustration. Inactual practice, the bottom surface of the sheet lies only a fewthousands of an inch above the surface of the microelectronic element,and deflects downwardly by only a few thousands of an inch when disk 61is applied. Additional force is applied to the disk 61 until thesheet-like element 40 contacts the microelectronic component 51. Thebond pads 42 in the example shown in FIG. 8 are now in contact with theterminal pads 50 of the microelectronic component 51. The assembly asshown in FIG. 7 is then heated in order to activate the bonding agentpresent at the interface between the bond pads 42 and the terminal pads50, metallurgically bonding those components (FIG. 9). During thisheating step, the sheet remains taut.

As noted, the bonding technique of the invention is especially suitedfor smaller component sizes wherein the significance of the variation inheight of the bond pads and the terminal pads is reduced. For example,this technique may be used for single-chip wafers or for waferscontaining a small array of chips, such as a three by three array. Forsuch application, the technique provides a low-cost, flexiblealternative to the hot air press bonding technique.

After the bond pads 42 are bonded to the terminal pads on the electricalcomponent 51, an encapsulant comprising a compliant dieletric layer 110,such a silicone, is injected between the sheet-like element 30 and themicroelectronic element 51. In a preferred embodiment of the invention,force of the pressurized encapsulant 110 acting on the sheet-likeelement 30 and the microelectronic component 51 separate those twoelements as the encapsulant is injected (FIG. 10). The relative motionof those two components separates the leads 41 from the sheet-likeelement 30, bending them to their final configuration. Such a lead 41 isshown in plan view in FIG. 11.

In an alternative embodiment, the leads 41 are bent and formed beforeinjecting the encapsulant 110. This technique is preferred in the casewhere straight leads (not shown) are used in place of the curved lead 41of FIG. 10. Straight leads are used where space is limited by a highterminal pad density of the microelectronic component. In thisembodiment, the assembly is placed in a fixture including an upperplaten for grasping the sheet-like element 30 and a lower platen forgrasping the microelectronic component 51. The platens may use ports forapplying vacuum to those components in order to grasp them. Thesheet-like element 30 is then displaced away from and parallel to themicroelectronic element component 51 in order to bend the lead 41. Thisprocess is especially suitable for leads requiring bending in both thehorizontal and vertical directions. The space between the sheet-likeelement 30 and the microelectronic element 51 is then filled with theencapsulant 110 as described above.

In either technique, the encapsulant 110 flows around and between eachof the leads 41, providing a resilient backing to apply an even force tothe terminals 44 upon assembly to a circuit board or other component.

Various other lead configurations may be used and still practice theinvention. In addition to the curved lead shown in plan view in FIG. 10,other geometries such as spiral leads, S-shaped leads, bent leads andleads having multiple traces may be used. Lead formation is additionallydescribed in U.S. Pat. No. 5,518,964, which has been incorporated byreference in this application.

These and other variations and combinations of the features discussedabove can be utilized without departing from the present invention asdefined by the claims. The foregoing description of the preferredembodiment should be taken as illustrating, rather than limiting, theinvention, as claimed.

What is claimed is:
 1. A method of mounting a sheet-like microelectronicelement, comprising:bonding the sheet-like element to an expansion ring;heating and expanding said expansion ring to stretch the sheet-likeelement taut; and bonding said sheet-like element to a frame ring havingan outside diameter less that an inside diameter of said expansion ring.2. The method as claimed in claim 1, wherein said expansion ringconsists essentially of aluminum.
 3. The method as claimed in claim 1,wherein said frame ring has a coefficient of thermal expansionapproximating that of silicon.
 4. The method as claimed in claim 1,wherein said frame ring consists essentially of molybdenum.
 5. Themethod as claimed in claim 4, wherein said expansion ring has acoefficient of thermal expansion greater that of molybdenum.
 6. Themethod as claimed in claim 1, further comprising the step of removingsaid expansion ring by severing the sheet-like element between saidexpansion ring and said frame ring.
 7. A method of bonding a pluralityof bond pads disposed on a flexible, sheet-like microelectronic elementto a plurality of contacts on a microelectronic component,comprising:mounting the flexible, sheet-like element on a frame ring;placing the microelectronic component on a rigid plate; placing saidframe ring on said rigid plate so that the sheet-like element overliesand is spaced away from the microelectronic component; aligning theplurality of bond pads with the plurality of contacts by moving theframe ring and the component in relation to one another; placing a diskon said sheet-like element, said disk having a diameter smaller than aninside diameter of said frame ring; applying downward pressure on saiddisk, whereby the plurality of bond pads are pressed against theplurality of contacts; and heating the plurality of bond pads and theplurality of contacts whereby a bonding agent at an interfacetherebetween is actuated.
 8. The method as claimed in claim 7, wheresaid frame plate consists essentially of molybdenum.
 9. The method asclaimed in claim 7, wherein said frame ring consists essentially ofmolybdenum.
 10. The method as claimed in claim 7, wherein themicroelectronic component is approximately circular, and said disk has adiameter approximately equal to that of the microelectronic component.11. The method as claimed in claim 7, wherein the step of heating theplurality of bond pads and the plurality of contacts comprises placingsaid rigid plate on a hot plate.
 12. The method as claimed in claim 7,wherein the step of aligning the plurality of contacts to the pluralityof bond pads comprises optical alignment using a vision system.
 13. Themethod as claimed in claim 7, wherein the disk consists essentially ofceramic.
 14. The method as claimed in claim 7, wherein the plurality ofbond pads are on tip ends of deformable leads.
 15. The method as claimedin claim 14, further comprising the step of bending the deformableleads.
 16. The method as claimed in claim 14, wherein the step ofbending the deformable leads further comprises injecting an encapsulantbetween said microelectronic component and said sheet-like element,whereby a pressure force of said encapsulant separates said componentfrom said element.
 17. The method as claimed in claim 14, wherein thestep of bending the deformable leads further comprises relativelydisplacing said sheet-like element and said microelectronic component intwo directions.
 18. A method of bonding a plurality of bond padsdisposed on a flexible, sheet-like microelectronic element to aplurality of contacts on a microelectronic component, comprising:bondingthe sheet-like element to an expansion ring; heating and expanding saidexpansion ring to stretch the sheet-like element taut; bonding saidsheet-like element to a frame ring, said frame ring having an outsidediameter less that an inside diameter of said expansion ring; placingthe microelectronic component on a rigid plate; placing said frame ringon said rigid plate so that the sheet-like element overlies themicroelectronic component; aligning the plurality of bond pads with theplurality of contacts by moving the frame ring; placing a disk on saidsheet-like element, said disk having a diameter smaller than an insidediameter of said frame ring; applying downward pressure on said disk,whereby the plurality of bond pads are pressed against the plurality ofcontacts; and heating the plurality of bond pads and the plurality ofcontacts whereby a bonding agent at an interface therebetween isactuated.
 19. The method as claimed in claim 18, wherein the rigid plateand the frame ring consist essentially of molybdenum and the expansionring consists essentially of aluminum.